Resin composition, prepreg, film with resin, metal foil with resin, metal-clad laminate, and wiring board

ABSTRACT

An aspect of the present invention is a resin composition containing a first styrene-based block copolymer having a hardness of 20 to 70, a polyphenylene ether compound having at least one of a group represented by the following Formula (1) and a group represented by the following Formula (2) in a molecule, and a curing agent.In Formula (1), p represents 0 to 10, Z represents an arylene group, and R1 to R3 each independently represent a hydrogen atom or an alkyl group.In Formula (2), R4 represents a hydrogen atom or an alkyl group.

TECHNICAL FIELD

The present invention relates to a resin composition, a prepreg, a filmwith resin, a metal foil with resin, a metal-clad laminate, and a wiringboard.

BACKGROUND ART

As the information processing quantity by various kinds of electronicequipment increases, mounting technologies such as high integration ofsemiconductor devices to be mounted, densification of wiring, andmulti-layering are progressing. In addition, wiring boards to be used invarious kinds of electronic equipment are required to be, for example,high-frequency compatible wiring boards such as a millimeter-wave radarboard for in-vehicle use. Substrate materials for forming insulatinglayers of wiring boards to be used in various kinds of electronicequipment are required to have a low dielectric constant and a lowdielectric loss tangent in order to increase the signal transmissionspeed and to decrease the signal transmission loss.

It is known that polyphenylene ether exhibits excellent low dielectricproperties such as a low dielectric constant and a low dielectric losstangent and exhibits excellent low dielectric properties such as a lowdielectric constant and a low dielectric loss tangent even in a highfrequency band (high frequency region) from the MHz band to the GHzband. For this reason, it has been investigated that polyphenylene etheris used, for example, as a high frequency molding material. Morespecifically, polyphenylene ether is preferably used as a substratematerial for forming an insulating layer of a wiring board to beequipped in electronic equipment utilizing a high frequency band.

As substrate materials for forming insulating layers of wiring boards,resin compositions containing elastomers such as hydrogenated styrenebutadiene styrene copolymer are used in order to improve the impactresistance of the insulating layers. Examples of such resin compositionscontaining elastomers include the resin composition described in PatentLiterature 1.

Patent Literature 1 describes a curable resin composition containing apredetermined vinyl compound having a polyphenylene ether skeleton and ahigh molecular weight substance having a weight average molecular weightof 10,000 or more such as a styrene-based thermoplastic elastomer asessential components.

The metal-clad laminate and the metal foil with resin used when a wiringboard or the like is manufactured include not only an insulating layerbut also a metal foil on the insulating layer. The wiring board alsoincludes not only an insulating layer but also wiring on the insulatinglayer. Examples of the wiring include wiring derived from a metal foilincluded in the metal-clad laminate or the like.

In recent years, particularly small portable devices such as mobilecommunication terminals and notebook PCs have rapidly becomemultifunctional, high-performance, thin and compact. To accompany this,the wiring boards used in these products are also required to have finerconductor wiring, multiple and thinner conductor wiring layers, andhigher performance of mechanical properties. In particular, as wiringboards become thinner, there is a problem that warpage of semiconductorpackages in which semiconductor chips are mounted on wiring boards islikely to occur and poor mounting is likely to occur. In order tosuppress the warpage of semiconductor packages in which semiconductorchips are mounted on wiring boards, the insulating layers are requiredto have a low coefficient of thermal expansion. Hence, substratematerials for forming insulating layers of wiring boards are required toprovide a cured product having a low coefficient of thermal expansion.

CITATION LIST Patent Literature

-   Patent Literature 1: JP 2006-83364 A

SUMMARY OF INVENTION

The present invention has been made in view of such circumstances, andan object thereof is to provide a resin composition, which provides acured product exhibiting low dielectric properties and a low coefficientof thermal expansion. Another object of the present invention is toprovide a prepreg, a film with resin, a metal foil with resin, ametal-clad laminate, and a wiring board which are obtained using theresin composition.

An aspect of the present invention is a resin composition containing afirst styrene-based block copolymer having a hardness of 20 to 70, apolyphenylene ether compound having at least one of a group representedby the following Formula (1) and a group represented by the followingFormula (2) in a molecule, and a curing agent.

In Formula (1), p represents 0 to 10, Z represents an arylene group, andR₁ to R₃ each independently represent a hydrogen atom or an alkyl group.

In Formula (2), R₄ represents a hydrogen atom or an alkyl group.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic sectional view illustrating an example of aprepreg according to an embodiment of the present invention.

FIG. 2 is a schematic sectional view illustrating an example of ametal-clad laminate according to an embodiment of the present invention.

FIG. 3 is a schematic sectional view illustrating an example of a wiringboard according to an embodiment of the present invention.

FIG. 4 is a schematic sectional view illustrating an example of a metalfoil with resin according to an embodiment of the present invention.

FIG. 5 is a schematic sectional view illustrating an example of a filmwith resin according to an embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS

As a result of extensive studies, the present inventors have found outthat the objects can be achieved by the following invention.

Hereinafter, embodiments according to the present invention will bedescribed, but the present invention is not limited thereto.

[Resin Composition]

The resin composition according to an aspect of the present invention isa resin composition containing a first styrene-based block copolymerhaving a hardness of 20 to 70 (20 or more and 70 or less), apolyphenylene ether compound having at least one of a group representedby the following Formula (1) and a group represented by the followingFormula (2) in the molecule, and a curing agent.

In Formula (1), p represents 0 to 10, Z represents an arylene group, andR₁ to R₃ each independently represent a hydrogen atom or an alkyl group.

In Formula (2), R₄ represents a hydrogen atom or an alkyl group.

First, it is considered that a cured product which maintains theexcellent low dielectric properties of polyphenylene ether is obtainedfrom the resin composition by curing the polyphenylene ether compoundtogether with the curing agent even though the first styrene-based blockcopolymer is contained. It is considered that a cured product having alow coefficient of thermal expansion is obtained since the resincomposition contains the first styrene-based block copolymer having ahardness of 20 to 70.

From the above, the resin composition provides a cured productexhibiting low dielectric properties and a low coefficient of thermalexpansion. As a substrate material for forming an insulating layer of awiring board that is required to be thin, a material having a lowerdielectric constant is required. In order to decrease the dielectricconstant of the substrate material, it is more effective to decrease thecontent of the inorganic filler since inorganic fillers such as silicahave a higher relative dielectric constant than organic resins, but thecoefficient of thermal expansion such as the coefficient of linearexpansion tends to increase when the amount of the inorganic filler isdecreased. The resin composition according to the present embodimentprovides a cured product having a sufficiently low coefficient ofthermal expansion when the amount of the inorganic filler added isdecreased and the dielectric constant is decreased.

(First Styrene-Based Block Copolymer)

The first styrene-based block copolymer is not particularly limited aslong as it is a styrene-based block copolymer having a hardness of 20 to70. The hardness of the first styrene-based block copolymer is 20 to 70as described above, and is preferably 30 to 60. When the firststyrene-based block copolymer is too hard (the hardness of the firststyrene-based block copolymer is too high), the elastic modulus of thecured product of the resin composition becomes too high, there is thus atendency that the effect acquired by adding the first styrene-basedblock copolymer, namely, the effect of decreasing the coefficient ofthermal expansion while maintaining low dielectric properties in thecured product of the resin composition cannot be sufficiently exerted.Hence, by containing a styrene-based block copolymer of which thehardness is within the above range, a resin composition is obtained,which becomes a cured product exhibiting low dielectric properties and alow coefficient of thermal expansion when being cured.

Examples of the hardness include a durometer hardness, more specificallya durometer hardness measured using a type A durometer in conformitywith JIS K 6253.

Examples of the first styrene-based block copolymer include amethylstyrene (ethylene/butylene) methylstyrene copolymer, amethylstyrene (ethylene-ethylene/propylene) methylstyrene copolymer, astyrene isoprene copolymer, a styrene isoprene styrene copolymer, astyrene (ethylene/butylene) styrene copolymer, a styrene(ethylene-ethylene/propylene) styrene copolymer, a styrene butadienestyrene copolymer, a styrene (butadiene/butylene) styrene copolymer, anda styrene isobutylene styrene copolymer, and the first styrene-basedblock copolymer may be any hydrogenated product of these copolymers.Among these, the first styrene-based block copolymer is preferably astyrene isoprene styrene copolymer or a styrene (ethylene/butylene)styrene copolymer. The first styrene-based block copolymers may be usedsingly or in combination of two or more kinds thereof.

In the first styrene-based block copolymer, a structural unit derivedfrom at least one of styrene and a styrene derivative is contained, andthe content thereof is preferably 1% to 25% by mass, more preferably 1%to 20% by mass, still more preferably 10% to 20% by mass. When thecontent is too low, the compatibility with the polyphenylene ethercompound becomes poor, and the contained components tend to be easilyseparated from each other when the resin composition is formed into avarnish. When the content is too high, the first styrene-based blockcopolymer becomes too hard (the hardness of the first styrene-basedblock copolymer becomes too high), and it tends to be difficult toobtain a cured product having a low coefficient of thermal expansion.

The elastic modulus of the first styrene-based block copolymer ispreferably 10 MPa or less, more preferably 6 MPa or less, still morepreferably 2 MPa or less. When the elastic modulus is too high, thefirst styrene-based block copolymer tends to be too hard, and there isthus a tendency that the effect of decreasing the coefficient of thermalexpansion while maintaining low dielectric properties in the curedproduct of the resin composition cannot be sufficiently exerted. Hence,by containing a styrene-based block copolymer of which the elasticmodulus is within the above range, a resin composition is obtained,which becomes a cured product exhibiting low dielectric properties and alow coefficient of thermal expansion when being cured. It is morepreferable as the elastic modulus of the first styrene-based blockcopolymer is lower as described above, but the lower limit of theelastic modulus is actually about 0.05 MPa. From this fact, the elasticmodulus of the first styrene-based block copolymer is preferably 0.05 to10 MPa.

Examples of the elastic modulus include a tensile modulus at 25° C., andmore specifically, a tensile modulus measured in conformity with JIS K6251.

The weight average molecular weight of the first styrene-based blockcopolymer is preferably 10,000 to 200,000, more preferably 50,000 to180,000. When the molecular weight is too low, the glass transitiontemperature of the cured product of the resin composition tends todecrease or the heat resistance thereof tends to decrease. When themolecular weight is too high, the viscosity when the resin compositionis formed into a varnish and the viscosity of the resin composition atthe time of heat molding tend to be too high. The weight averagemolecular weight may be measured by a general molecular weightmeasurement method, and specific examples thereof include a valuemeasured by gel permeation chromatography (GPC).

(Polyphenylene Ether Compound)

The polyphenylene ether compound is not particularly limited as long asit is a polyphenylene ether compound having at least one of the grouprepresented by Formula (1) and the group represented by Formula (2) inthe molecule. Specific examples of the polyphenylene ether compoundinclude a polyphenylene ether compound having at least one of the grouprepresented by Formula (1) and the group represented by Formula (2) atthe molecular terminal. More specific examples of the polyphenyleneether compound include a polyphenylene ether compound of which theterminal is modified with at least one of the group represented byFormula (1) and the group represented by Formula (2). Among these, it ispreferable to contain a polyphenylene ether compound having the grouprepresented by Formula (2) in the molecule. When a polyphenylene ethercompound having the group represented by Formula (2) in the molecule iscontained, the obtained resin composition provides a cured productexhibiting low dielectric properties and a low coefficient of thermalexpansion and a high glass transition temperature.

In Formula (1), p represents 0 to 10. In addition, Z represents anarylene group. R₁ to R₃ are independent of each other. In other words,R₁ to R₃ may be the same group as or different groups from each other.R₁ to R₃ represent a hydrogen atom or an alkyl group.

In a case where p in Formula (1) is 0, it indicates that Z is directlybonded to the terminal of polyphenylene ether.

This arylene group is not particularly limited. Examples of this arylenegroup include a monocyclic aromatic group such as a phenylene group, anda polycyclic aromatic group in which the aromatic is not a single ringbut a polycyclic aromatic such as a naphthalene ring. In addition, thisarylene group also includes a derivative in which a hydrogen atom bondedto an aromatic ring is substituted with a functional group such as analkenyl group, an alkynyl group, a formyl group, an alkylcarbonyl group,an alkenylcarbonyl group, or an alkynylcarbonyl group. The alkyl groupis not particularly limited and is, for example, preferably an alkylgroup having 1 to 18 carbon atoms, more preferably an alkyl group having1 to 10 carbon atoms. Specific examples thereof include a methyl group,an ethyl group, a propyl group, a hexyl group, and a decyl group.

In Formula (2), R₄ represents a hydrogen atom or an alkyl group. Thealkyl group is not particularly limited and is, for example, preferablyan alkyl group having 1 to 18 carbon atoms, more preferably an alkylgroup having 1 to 10 carbon atoms. Specific examples thereof include amethyl group, an ethyl group, a propyl group, a hexyl group, and a decylgroup.

Preferred specific examples of the group represented by Formula (1)include a vinylbenzyl group (ethenylbenzyl group) represented by thefollowing Formula (3) and a vinylphenyl group. Examples of thevinylbenzyl group include an o-ethenylbenzyl group, a p-ethenylbenzylgroup, and a m-ethenylbenzyl group. Examples of the group represented byFormula (2) include an acryloyl group and a methacryloyl group.

The polyphenylene ether compound has at least one of the grouprepresented by Formula (1) and the group represented by Formula (2) inthe molecule, and may have one or two or more as these groups. Thepolyphenylene ether compound may have, for example, any of ano-ethenylbenzyl group, a p-ethenylbenzyl group, and an m-ethenylbenzylgroup, or two or three kinds thereof.

The polyphenylene ether compound has a polyphenylene ether chain in themolecule and preferably has, for example, a repeating unit representedby the following Formula (4) in the molecule.

In Formula (4), t represents 1 to 50. R₅ to R₈ are independent of eachother. In other words, R₅ to R₈ may be the same group as or differentgroups from each other. R₅ to R₈ represent a hydrogen atom, an alkylgroup, an alkenyl group, an alkynyl group, a formyl group, analkylcarbonyl group, an alkenylcarbonyl group, or an alkynylcarbonylgroup. Among these, a hydrogen atom and an alkyl group are preferable.

Specific examples of the respective functional groups mentioned in R₅ toR₈ include the following.

The alkyl group is not particularly limited and is, for example,preferably an alkyl group having 1 to 18 carbon atoms, more preferablyan alkyl group having 1 to 10 carbon atoms. Specific examples thereofinclude a methyl group, an ethyl group, a propyl group, a hexyl group,and a decyl group.

The alkenyl group is not particularly limited and is, for example,preferably an alkenyl group having 2 to 18 carbon atoms, more preferablyan alkenyl group having 2 to 10 carbon atoms. Specific examples thereofinclude a vinyl group, an allyl group, and a 3-butenyl group.

The alkynyl group is not particularly limited and is, for example,preferably an alkynyl group having 2 to 18 carbon atoms, more preferablyan alkynyl group having 2 to 10 carbon atoms. Specific examples thereofinclude an ethynyl group and a prop-2-yn-1-yl group (propargyl group).

The alkylcarbonyl group is not particularly limited as long as it is acarbonyl group substituted with an alkyl group and is, for example,preferably an alkylcarbonyl group having 2 to 18 carbon atoms, morepreferably an alkylcarbonyl group having 2 to 10 carbon atoms. Specificexamples thereof include an acetyl group, a propionyl group, a butyrylgroup, an isobutyryl group, a pivaloyl group, a hexanoyl group, anoctanoyl group, and a cyclohexylcarbonyl group.

The alkenylcarbonyl group is not particularly limited as long as it is acarbonyl group substituted with an alkenyl group and is, for example,preferably an alkenylcarbonyl group having 3 to 18 carbon atoms, morepreferably an alkenylcarbonyl group having 3 to 10 carbon atoms.Specific examples thereof include an acryloyl group, a methacryloylgroup, and a crotonoyl group.

The alkynylcarbonyl group is not particularly limited as long as it is acarbonyl group substituted with an alkynyl group and is, for example,preferably an alkynylcarbonyl group having 3 to 18 carbon atoms, morepreferably an alkynylcarbonyl group having 3 to 10 carbon atoms.Specific examples thereof include a propioloyl group.

The weight average molecular weight (Mw) of the polyphenylene ethercompound is not particularly limited. Specifically, the weight averagemolecular weight is preferably 500 to 5000, more preferably 800 to 4000,and still more preferably 1000 to 3000. Note that the weight averagemolecular weight here may be measured by a general molecular weightmeasurement method, and specific examples thereof include a valuemeasured by gel permeation chromatography (GPC). In a case where thepolyphenylene ether compound has a repeating unit represented by Formula(4) in the molecule, t is preferably a numerical value so that theweight average molecular weight of the polyphenylene ether compound isin such a range. Specifically, t is preferably 1 to 50.

When the weight average molecular weight of the polyphenylene ethercompound is in such a range, the polyphenylene ether compound exhibitsthe excellent low dielectric properties of polyphenylene ether and notonly imparts superior heat resistance to the cured product but alsoexhibits excellent moldability. This is considered to be due to thefollowing. When the weight average molecular weight of ordinarypolyphenylene ether is in such a range, the heat resistance of the curedproduct tends to decrease since the molecular weight is relatively low.With regard to this point, it is considered that since the polyphenyleneether compound according to the present embodiment has at least one ofthe group represented by Formula (1) and the group represented byFormula (2) in the molecule, a cured product exhibiting sufficientlyhigh heat resistance is obtained. When the weight average molecularweight of the polyphenylene ether compound is in such a range, thepolyphenylene ether compound has a relatively low molecular weight andis thus considered to exhibit excellent moldability. Hence, it isconsidered that such a polyphenylene ether compound not only impartssuperior heat resistance to the cured product but also exhibitsexcellent moldability.

In the polyphenylene ether compound, the average number (number ofterminal functional groups) of at least one (substituent) of the grouprepresented by Formula (1) and the group represented by Formula (2) perone molecule of the polyphenylene ether compound is not particularlylimited. Specifically, the number of terminal functional groups ispreferably 1 to 5, more preferably 1 to 3, still more preferably 1.5 to3. When this number of terminal functional groups is too small,sufficient heat resistance of the cured product tends to be hardlyattained. In addition, when the number of terminal functional groups istoo large, the reactivity is too high and, for example, troubles such asdeterioration in the storage stability of the resin composition ordeterioration in the fluidity of the resin composition may occur. Inother words, when such a polyphenylene ether compound is used, forexample, molding defects such as generation of voids at the time ofmultilayer molding occur by insufficient fluidity and the like and aproblem of moldability that a highly reliable printed wiring board ishardly obtained may occur.

The number of terminal functional groups in the polyphenylene ethercompound includes a numerical value expressing the average value of thesubstituents per one molecule of all the polyphenylene ether compoundspresent in 1 mole of the polyphenylene ether compound. This number ofterminal functional groups can be determined by, for example, measuringthe number of hydroxyl groups remaining in the obtained polyphenyleneether compound and calculating the number of hydroxyl groups decreasedfrom the number of hydroxyl groups in the polyphenylene ether beforehaving (before being modified with) the substituent. The number ofhydroxyl groups decreased from the number of hydroxyl groups in thepolyphenylene ether before being modified is the number of terminalfunctional groups. Moreover, with regard to the method for measuring thenumber of hydroxyl groups remaining in the polyphenylene ether compound,the number of hydroxyl groups can be determined by adding a quaternaryammonium salt (tetraethylammonium hydroxide) to be associated with ahydroxyl group to a solution of the polyphenylene ether compound andmeasuring the UV absorbance of the mixed solution.

The intrinsic viscosity of the polyphenylene ether compound is notparticularly limited. Specifically, the intrinsic viscosity ispreferably 0.03 to 0.12 dl/g, more preferably 0.04 to 0.11 dl/g, stillmore preferably 0.06 to 0.095 dl/g. When the intrinsic viscosity is toolow, the molecular weight tends to be low and low dielectric propertiessuch as a low dielectric constant and a low dielectric loss tangent tendto be hardly attained. In addition, when the intrinsic viscosity is toohigh, the viscosity is high, sufficient fluidity is not attained, andthe moldability of the cured product tends to deteriorate. Hence, whenthe intrinsic viscosity of the polyphenylene ether compound is in theabove range, excellent heat resistance and moldability of the curedproduct can be realized.

Note that the intrinsic viscosity here is an intrinsic viscositymeasured in methylene chloride at 25° C. and more specifically is, forexample, a value attained by measuring the intrinsic viscosity of amethylene chloride solution (liquid temperature: 25° C.) at 0.18 g/45 mlusing a viscometer. Examples of the viscometer include AVS500 ViscoSystem manufactured by SCHOTT Instruments GmbH.

Examples of the polyphenylene ether compound include a polyphenyleneether compound represented by the following Formula (5) and apolyphenylene ether compound represented by the following Formula (6).As the polyphenylene ether compound, these polyphenylene ether compoundsmay be used singly or these two kinds of polyphenylene ether compoundsmay be used in combination.

In Formulas (5) and (6), R₉ to R₁₆ and R₁₇ to R₂₄ each independentlyrepresent a hydrogen atom, an alkyl group, an alkenyl group, an alkynylgroup, a formyl group, an alkylcarbonyl group, an alkenylcarbonyl group,or an alkynylcarbonyl group. X₁ and X₂ each independently represent thegroup represented by Formula (1) or the group represented by Formula(2). A and B represent a repeating unit represented by the followingFormula (7) and a repeating unit represented by the following Formula(8), respectively. In Formula (6), Y represents a linear, branched, orcyclic hydrocarbon having 20 or less carbon atoms.

In Formulas (7) and (8), m and n each represent 0 to 20. R₂₅ to R₂₈ andR₂₉ to R₃₂ each independently represent a hydrogen atom, an alkyl group,an alkenyl group, an alkynyl group, a formyl group, an alkylcarbonylgroup, an alkenylcarbonyl group, or an alkynylcarbonyl group.

The polyphenylene ether compound represented by Formula (5) and thepolyphenylene ether compound represented by Formula (6) are notparticularly limited as long as they are compounds satisfying theconfiguration. Specifically, in Formulas (5) and (6), R₉ to R₁₆ and R₁₇to R₂₄ are independent of each other as described above. In other words,R₉ to R₁₆ and R₁₇ to R₂₄ may be the same group as or different groupsfrom each other. R₉ to R₁₆ and R₁₇ to R₂₄ represent a hydrogen atom, analkyl group, an alkenyl group, an alkynyl group, a formyl group, analkylcarbonyl group, an alkenylcarbonyl group, or an alkynylcarbonylgroup. Among these, a hydrogen atom and an alkyl group are preferable.

In Formulas (7) and (8), m and n each preferably represent 0 to 20 asdescribed above. It is preferable that m and n represent numericalvalues so that the sum of m and n is 1 to 30. Hence, it is morepreferable that m represents 0 to 20, n represents 0 to 20, and the sumof m and n represents 1 to 30. R₂₅ to R₂₈ and R₂₉ to R₃₂ are independentof each other. In other words, R₂₅ to R₂₈ and R₂₉ to R₃₂ may be the samegroup as or different groups from each other. R₂₅ to R₂₈ and R₂₉ to R₃₂represent a hydrogen atom, an alkyl group, an alkenyl group, an alkynylgroup, a formyl group, an alkylcarbonyl group, an alkenylcarbonyl group,or an alkynylcarbonyl group. Among these, a hydrogen atom and an alkylgroup are preferable.

R₉ to R₃₂ are the same as R₅ to R₈ in Formula (4).

In Formula (6), Y represents a linear, branched, or cyclic hydrocarbonhaving 20 or less carbon atoms as described above. Examples of Y includea group represented by the following Formula (9).

In Formula (9), R₃₃ and R₃₄ each independently represent a hydrogen atomor an alkyl group. Examples of the alkyl group include a methyl group.Examples of the group represented by Formula (9) include a methylenegroup, a methylmethylene group, and a dimethylmethylene group. Amongthese, a dimethylmethylene group is preferable.

In Formulas (5) and (6), X₁ and X₂ are each independently the grouprepresented by Formula (1) or the group represented by Formula (2). Inthe polyphenylene ether compound represented by Formula (5) and thepolyphenylene ether compound represented by Formula (6), X₁ and X₂ maybe the same group as or different groups from each other.

More specific examples of the polyphenylene ether compound representedby Formula (5) include a polyphenylene ether compound represented by thefollowing Formula (10).

More specific examples of the polyphenylene ether compound representedby Formula (6) include a polyphenylene ether compound represented by thefollowing Formula (11) and a polyphenylene ether compound represented bythe following Formula (12).

In Formulas (10) to (12), m and n are the same as m and n in Formulas(7) and (8). In Formulas (10) and (11), R₁ to R₃, p, and Z are the sameas R₁ to R₃, p, and Z in Formula (1). In Formulas (11) and (12), Y isthe same as Y in the above (6). In Formula (12), R₄ is the same as R₁ inFormula (2).

The method for synthesizing the polyphenylene ether compound used in thepresent embodiment is not particularly limited as long as apolyphenylene ether compound having at least one of the grouprepresented by Formula (1) and the group represented by Formula (2) inthe molecule can be synthesized. Here, a method for synthesizing apolyphenylene ether compound of which the terminal is modified with atleast one of the group represented by Formula (1) and the grouprepresented by Formula (2) will be described. Specific examples of thismethod include a method in which polyphenylene ether is reacted with acompound in which at least one of the group represented by Formula (1)and the group represented by Formula (2) is bonded to a halogen atom.Specific examples of the halogen atom include a chlorine atom, a bromineatom, an iodine atom, and a fluorine atom. Among these, a chlorine atomis preferable. More specific examples of the compound, in which at leastone of the group represented by Formula (1) and the group represented byFormula (2) is bonded to a halogen atom, include o-chloromethylstyrene,p-chloromethylstyrene, and m-chloromethylstyrene. The compounds, inwhich at least one of the group represented by Formula (1) and the grouprepresented by Formula (2) is bonded to a halogen atom, may be usedsingly or in combination of two or more kinds thereof. For example,o-chloromethylstyrene, p-chloromethylstyrene, and m-chloromethylstyrenemay be used singly or in combination of two or three kinds thereof.

Polyphenylene ether which is a raw material is not particularly limitedas long as a predetermined modified polyphenylene ether compound can befinally synthesized. Specific examples thereof include those containingpolyphenylene ether containing 2,6-dimethylphenol and at least one of abifunctional phenol and a trifunctional phenol and polyphenylene ethersuch as poly(2,6-dimethyl-1,4-phenylene oxide) as a main component. Thebifunctional phenol is a phenol compound having two phenolic hydroxylgroups in the molecule, and examples thereof include tetramethylbisphenol A. The trifunctional phenol is a phenol compound having threephenolic hydroxyl groups in the molecule.

Examples of the method for synthesizing the modified polyphenylene ethercompound include the methods described above. Specifically, suchpolyphenylene ether and the compound, in which at least one of the grouprepresented by Formula (1) and the group represented by Formula (2) isbonded to a halogen atom, are dissolved in a solvent and stirred. Bydoing so, polyphenylene ether reacts with the compound, in which atleast one of the group represented by Formula (1) and the grouprepresented by Formula (2) is bonded to a halogen atom, and the modifiedpolyphenylene ether compound to be used in the present embodiment isobtained.

The reaction is preferably conducted in the presence of an alkali metalhydroxide. By doing so, it is considered that this reaction suitablyproceeds. This is considered to be because the alkali metal hydroxidefunctions as a dehydrohalogenating agent, specifically, adehydrochlorinating agent. In other words, it is considered that thealkali metal hydroxide eliminates the hydrogen halide from the phenolgroup in polyphenylene ether and the compound in which at least one ofthe group represented by Formula (1) and the group represented byFormula (2) is bonded to a halogen atom, and by doing so, at least oneof the group represented by Formula (1) and the group represented byFormula (2) is bonded to the oxygen atom of the phenol group instead ofthe hydrogen atom of the phenol group in the polyphenylene ether.

The alkali metal hydroxide is not particularly limited as long as it canact as a dehalogenating agent, and examples thereof include sodiumhydroxide. In addition, the alkali metal hydroxide is usually used inthe form of an aqueous solution and is specifically used as an aqueoussodium hydroxide solution.

The reaction conditions such as reaction time and reaction temperaturealso vary depending on the compound in which at least one of the grouprepresented by Formula (1) and the group represented by Formula (2) isbonded to a halogen atom, and the like, and are not particularly limitedas long as they are conditions under which the reaction as describedabove suitably proceeds. Specifically, the reaction temperature ispreferably room temperature to 100° C., more preferably 30° C. to 100°C. The reaction time is preferably 0.5 to 20 hours, more preferably 0.5to 10 hours.

The solvent used at the time of the reaction is not particularly limitedas long as it can dissolve polyphenylene ether and the compound in whichat least one of the group represented by Formula (1) and the grouprepresented by Formula (2) is bonded to a halogen atom, and does notinhibit the reaction of polyphenylene ether with the compound, in whichat least one of the group represented by Formula (1) and the grouprepresented by Formula (2) is bonded to a halogen atom. Specificexamples thereof include toluene.

The above reaction is preferably conducted in the presence of not onlyan alkali metal hydroxide but also a phase transfer catalyst. In otherwords, the above reaction is preferably conducted in the presence of analkali metal hydroxide and a phase transfer catalyst. By doing so, it isconsidered that the above reaction more suitably proceeds. This isconsidered to be due to the following. This is considered to be becausethe phase transfer catalyst is a catalyst which has a function of takingin the alkali metal hydroxide, is soluble in both phases of a phase of apolar solvent such as water and a phase of a non-polar solvent such asan organic solvent, and can transfer between these phases. Specifically,in a case where an aqueous sodium hydroxide solution is used as analkali metal hydroxide and an organic solvent, such as toluene, which isincompatible with water is used as a solvent, it is considered that evenwhen the aqueous sodium hydroxide solution is dropped into the solventsubjected to the reaction, the solvent and the aqueous sodium hydroxidesolution are separated from each other and the sodium hydroxide ishardly transferred to the solvent. In that case, it is considered thatthe aqueous sodium hydroxide solution added as an alkali metal hydroxidehardly contributes to the promotion of the reaction. In contrast, whenthe reaction is conducted in the presence of an alkali metal hydroxideand a phase transfer catalyst, it is considered that the alkali metalhydroxide is transferred to the solvent in the state of being taken inthe phase transfer catalyst and the aqueous sodium hydroxide solution islikely to contribute to the promotion of the reaction. For this reason,when the reaction is conducted in the presence of an alkali metalhydroxide and a phase transfer catalyst, it is considered that the abovereaction more suitably proceeds.

The phase transfer catalyst is not particularly limited, and examplesthereof include quaternary ammonium salts such as tetra-n-butylammoniumbromide.

The resin composition to be used in the present embodiment preferablycontains a modified polyphenylene ether compound obtained as describedabove as the polyphenylene ether compound.

(Curing Agent)

The curing agent is a curing agent capable of reacting with thepolyphenylene ether compound and curing the resin composition containingthe polyphenylene ether compound. The curing agent is not particularlylimited as long as it is a curing agent capable of curing a resincomposition containing the polyphenylene ether compound. Examples of thecuring agent include styrene, styrene derivatives, a compound having anacryloyl group in the molecule, a compound having a methacryloyl groupin the molecule, a compound having a vinyl group in the molecule, acompound having an allyl group in the molecule, a compound having anacenaphthylene structure in the molecule, a compound having a maleimidegroup in the molecule, and an isocyanurate compound having anisocyanurate group in the molecule.

Examples of the styrene derivatives include bromostyrene anddibromostyrene.

The compound having an acryloyl group in the molecule is an acrylatecompound. Examples of the acrylate compound include a monofunctionalacrylate compound having one acryloyl group in the molecule and apolyfunctional acrylate compound having two or more acryloyl groups inthe molecule. Examples of the monofunctional acrylate compound includemethyl acrylate, ethyl acrylate, propyl acrylate, and butyl acrylate.Examples of the polyfunctional acrylate compound include diacrylatecompounds such as tricyclodecanedimethanol diacrylate.

The compound having a methacryloyl group in the molecule is amethacrylate compound. Examples of the methacrylate compound include amonofunctional methacrylate compound having one methacryloyl group inthe molecule and a polyfunctional methacrylate compound having two ormore methacryloyl groups in the molecule. Examples of the monofunctionalmethacrylate compound include methyl methacrylate, ethyl methacrylate,propyl methacrylate, and butyl methacrylate. Examples of thepolyfunctional methacrylate compound include dimethacrylate compoundssuch as tricyclodecanedimethanol dimethacrylate, and trimethacrylatecompounds such as trimethylolpropane trimethacrylate.

The compound having a vinyl group in the molecule is a vinyl compound.Examples of the vinyl compound include a monofunctional vinyl compound(monovinyl compound) having one vinyl group in the molecule and apolyfunctional vinyl compound having two or more vinyl groups in themolecule. Examples of the polyfunctional vinyl compound includedivinylbenzene and polybutadiene.

The compound having an allyl group in the molecule is an allyl compound.Examples of the allyl compound include a monofunctional allyl compoundhaving one allyl group in the molecule and a polyfunctional allylcompound having two or more allyl groups in the molecule. Examples ofthe polyfunctional allyl compound include triallyl isocyanuratecompounds such as triallyl isocyanurate (TAIC), diallyl bisphenolcompounds, and diallyl phthalate (DAP).

The compound having an acenaphthylene structure in the molecule is anacenaphthylene compound. Examples of the acenaphthylene compound includeacenaphthylene, alkylacenaphthylenes, halogenated acenaphthylenes, andphenylacenaphthylenes. Examples of the alkyl acenaphthylenes include1-methyl acenaphthylene, 3-methyl acenaphthylene, 4-methylacenaphthylene, 5-methyl acenaphthylene, 1-ethyl acenaphthylene, 3-ethylacenaphthylene, 4-ethyl acenaphthylene, and 5-ethyl acenaphthylene.Examples of the halogenated acenaphthylenes include1-chloroacenaphthylene, 3-chloroacenaphthylene, 4-chloroacenaphthylene,5-chloroacenaphthylene, 1-bromoacenaphthylene, 3-bromoacenaphthylene,4-bromoacenaphthylene, and 5-bromoacenaphthylene. Examples of thephenylacenaphthylenes include 1-phenylacenaphthylene,3-phenylacenaphthylene, 4-phenylacenaphthylene, and5-phenylacenaphthylene. The acenaphthylene compound may be amonofunctional acenaphthylene compound having one acenaphthylenestructure in the molecule as described above or may be a polyfunctionalacenaphthylene compound having two or more acenaphthylene structures inthe molecule.

The compound having a maleimide group in the molecule is a maleimidecompound. Examples of the maleimide compound include a monofunctionalmaleimide compound having one maleimide group in the molecule, apolyfunctional maleimide compound having two or more maleimide groups inthe molecule, and a modified maleimide compound. Examples of themodified maleimide compound include a modified maleimide compound inwhich a part of the molecule is modified with an amine compound, amodified maleimide compound in which a part of the molecule is modifiedwith a silicone compound, and a modified maleimide compound in which apart of the molecule is modified with an amine compound and a siliconecompound.

The compound having an isocyanurate group in the molecule is anisocyanurate compound. Examples of the isocyanurate compound include acompound having an alkenyl group in the molecule (alkenyl isocyanuratecompound), and examples thereof include a trialkenyl isocyanuratecompound such as triallyl isocyanurate (TAIC).

Among the above, the curing agent preferably contains, for example, anallyl compound having an allyl group in the molecule. As the allylcompound, an allyl isocyanurate compound having two or more allyl groupsin the molecule is preferable, and triallyl isocyanurate (TAIC) is morepreferable.

As the curing agent, the above curing agents may be used singly or incombination of two or more kinds thereof.

The weight average molecular weight of the curing agent is notparticularly limited and is, for example, preferably 100 to 5000, morepreferably 100 to 4000, still more preferably 100 to 3000. When theweight average molecular weight of the curing agent is too low, thecuring agent may easily volatilize from the compounding component systemof the resin composition. When the weight average molecular weight ofthe curing agent is too high, the viscosity of the varnish of the resincomposition and the melt viscosity at the time of heat molding may betoo high. Hence, a resin composition imparting superior heat resistanceto the cured product is obtained when the weight average molecularweight of the curing agent is within such a range. It is considered thatthis is because the resin composition containing the polyphenylene ethercompound can be suitably cured by the reaction of the curing agent withthe polyphenylene ether compound. Note that the weight average molecularweight here may be measured by a general molecular weight measurementmethod, and specific examples thereof include a value measured by gelpermeation chromatography (GPC).

The average number (number of functional groups) of the functionalgroups which contribute to the reaction of the curing agent with thepolyphenylene ether compound per one molecule of the curing agent variesdepending on the weight average molecular weight of the curing agent,but is, for example, preferably 1 to 20, more preferably 2 to 18. Whenthis number of functional groups is too small, sufficient heatresistance of the cured product tends to be hardly attained. When thenumber of functional groups is too large, the reactivity is too highand, for example, troubles such as a decrease in the storage stabilityof the resin composition or a decrease in the fluidity of the resincomposition may occur.

(Content)

The content of the first styrene-based block copolymer is preferably 20to 60 parts by mass, more preferably 25 to 55 parts by mass with respectto 100 parts by mass of the sum of the first styrene-based blockcopolymer, the polyphenylene ether compound, and the curing agent. Thecontent of the polyphenylene ether compound is preferably 20 to 75 partsby mass, more preferably 30 to 70 parts by mass with respect to 100parts by mass of the sum of the first styrene-based block copolymer, thepolyphenylene ether compound, and the curing agent. The content of thecuring agent is preferably 1 to 50 parts by mass, more preferably 5 to40 parts by mass with respect to 100 parts by mass of the sum of thefirst styrene-based block copolymer, the polyphenylene ether compound,and the curing agent. When the content of each of the firststyrene-based block copolymer, the polyphenylene ether compound, and thecuring agent is within the above range, a resin composition is obtained,which becomes a cured product having a lower coefficient of thermalexpansion while maintaining excellent low dielectric properties whenbeing cured.

(Second Styrene-Based Block Copolymer)

The resin composition according to the present embodiment may containthe second styrene-based block copolymer as long as the effects of thepresent invention are not impaired. The second styrene-based blockcopolymer is not particularly limited as long as it is a styrene-basedblock copolymer having a hardness of more than 70. The hardness of thesecond styrene-based block copolymer is more than 70 as described above,and is preferably more than 70 and 100 or less. When the hardness is 70or less, the difference in hardness between the first and secondstyrene-based block copolymers becomes small, and there is thus atendency that the effect acquired by adding the second styrene-basedblock copolymer, namely, the effect of decreasing the coefficient ofthermal expansion while maintaining low dielectric properties in thecured product of the resin composition and of making it difficult forthe contained components to be separated from each other when the resincomposition is fainted into a varnish cannot be sufficiently exerted.Hence, by containing a styrene-based block copolymer of which thehardness is within the above range together with the first styrene-basedblock copolymer, a resin composition is obtained, which becomes a curedproduct exhibiting low dielectric properties and a low coefficient ofthermal expansion when being cured and is formed into a varnish in whichthe contained components are hardly separated from each other.

The elastic modulus of the second styrene-based block copolymer ispreferably more than 10 MPa, more preferably 20 or more. When theelastic modulus is 10 MPa or less, the difference in elastic modulusbetween the first and second styrene-based block copolymers becomessmall, and there is thus a tendency that the effect acquired by addingthe second styrene-based block copolymer, namely, the effect ofdecreasing the coefficient of thermal expansion while maintaining lowdielectric properties in the cured product of the resin composition andof making it difficult for the contained components to be separated fromeach other when the resin composition is formed into a varnish cannot besufficiently exerted. Hence, by containing a styrene-based blockcopolymer of which the elastic modulus is within the above rangetogether with the first styrene-based block copolymer, a resincomposition is obtained, which becomes a cured product exhibiting lowdielectric properties and a low coefficient of thermal expansion whenbeing cured and is formed into a varnish in which the containedcomponents are hardly separated from each other. As described above, theelastic modulus of the second styrene-based block copolymer ispreferably more than 10 MPa, and the upper limit thereof is notparticularly limited but is, for example, preferably 200 MPa or less,more preferably 70 MPa or less.

Examples of the second styrene-based block copolymer include amethylstyrene (ethylene/butylene) methylstyrene copolymer, amethylstyrene (ethylene-ethylene/propylene) methylstyrene copolymer, astyrene isoprene copolymer, a styrene isoprene styrene copolymer, astyrene (ethylene/butylene) styrene copolymer, a styrene(ethylene-ethylene/propylene) styrene copolymer, a styrene butadienestyrene copolymer, a styrene (butadiene/butylene) styrene copolymer, anda styrene isobutylene styrene copolymer, and the second styrene-basedblock copolymer may be any hydrogenated product of these copolymers.Among these, the second styrene-based block copolymer is preferably amethylstyrene (ethylene/butylene) methylstyrene copolymer, a styrene(ethylene/butylene) styrene copolymer, and a styrene isobutylene styrenecopolymer. The second styrene-based block copolymers may be used singlyor in combination of two or more kinds thereof. It is preferable tocontain at least one selected from the group consisting of.

In the second styrene-based block copolymer, a structural unit derivedfrom at least one of styrene and a styrene derivative is contained, andthe content thereof is preferably 25% to 70% by mass, more preferably30% to 65% by mass. When the content is too low, the compatibility withthe polyphenylene ether compound becomes poor, and the containedcomponents tend to be easily separated from each other when the resincomposition is formed into a varnish. When the content is too high, thecompatibility with the first styrene-based block copolymer becomes poorand it tends to be difficult to obtain a varnish in a stable layeredstate.

The weight average molecular weight of the second styrene-based blockcopolymer is preferably 10,000 to 200,000, more preferably 50,000 to180,000. When the molecular weight is too low, the glass transitiontemperature of the cured product of the resin composition tends todecrease or the heat resistance thereof tends to decrease. When themolecular weight is too high, the viscosity when the resin compositionis formed into a varnish and the viscosity of the resin composition atthe time of heat molding tend to be too high.

The resin composition may not contain the second styrene-based blockcopolymer, but the content of the second styrene-based block copolymerin the case of being contained is preferably 1 to 50 parts by mass, morepreferably 1 to 40 parts by mass with respect to 100 parts by mass ofthe sum of the first styrene-based block copolymer and the secondstyrene-based block copolymer. The total content of the firststyrene-based block copolymer and the second styrene-based blockcopolymer is preferably 20 to 60 parts by mass, more preferably 25 to 55parts by mass with respect to 100 parts by mass of the sum of the firststyrene-based block copolymer, the polyphenylene ether compound, thecuring agent, and the second styrene-based block copolymer. When thecontent of the second styrene-based block copolymer in the case of beingcontained is within the above range, a resin composition is obtained,which becomes a cured product exhibiting low dielectric properties and alow coefficient of thermal expansion when being cured and is formed intoa varnish in which the contained components are hardly separated fromeach other.

(Other Components)

As described above, the resin composition according to the presentembodiment may contain the second styrene-based block copolymer, ifnecessary, as long as the effects of the present invention are notimpaired. The resin composition according to the present embodiment maycontain components (other components) other than the first styrene-basedblock copolymer, the polyphenylene ether compound, the curing agent, andthe second styrene-based block copolymer, if necessary, as long as theeffects of the present invention are not impaired. As other componentscontained in the resin composition according to the present embodiment,for example, additives such as a silane coupling agent, a flameretardant, an initiator, a curing accelerator, an antifoaming agent, anantioxidant, a polymerization inhibitor, a polymerization retarder, adispersant, a leveling agent, a heat stabilizer, an antistatic agent, anultraviolet absorber, a dye or pigment, a lubricant, and a filler may befurther contained. The resin composition may contain thermosettingresins such as an epoxy resin, an unsaturated polyester resin, and athermosetting polyimide resin in addition to the polyphenylene ethercompound.

As described above, the resin composition according to the presentembodiment may contain a flame retardant. The flame retardancy of acured product of the resin composition can be enhanced by containing aflame retardant. The flame retardant is not particularly limited.Specifically, in the field in which halogen-based flame retardants suchas bromine-based flame retardants are used, for example,ethylenedipentabromobenzene, ethylenebistetrabromoimide,decabromodiphenyloxide, and tetradecabromodiphenoxybenzene which have amelting point of 300° C. or more are preferable. It is considered thatthe elimination of halogen at a high temperature and the decrease inheat resistance can be suppressed by the use of a halogen-based flameretardant. In the field of being required to be free of halogen, aphosphoric ester-based flame retardant, a phosphazene-based flameretardant, a bis(diphenylphosphine oxide)-based flame retardant, and aphosphinate-based flame retardant are exemplified. Specific examples ofthe phosphoric ester-based flame retardant include a condensedphosphoric ester such as dixylenyl phosphate. Specific examples of thephosphazene-based flame retardant include phenoxyphosphazene. Specificexamples of the bis(diphenylphosphine oxide)-based flame retardantinclude xylylenebis(diphenylphosphine oxide). Specific examples of thephosphinate-based flame retardant include metal phosphinates such asaluminum dialkyl phosphinate. As the flame retardant, the respectiveflame retardants exemplified may be used singly or in combination of twoor more kinds thereof.

As described above, the resin composition according to the presentembodiment may contain a silane coupling agent. The silane couplingagent may be contained in the resin composition or may be contained as asilane coupling agent covered on the inorganic filler to be contained inthe resin composition for surface treatment in advance. Among these, itis preferable that the silane coupling agent is contained as a silanecoupling agent covered on the inorganic filler for surface treatment inadvance, and it is more preferable that the silane coupling agent iscontained as a silane coupling agent covered on the inorganic filler forsurface treatment in advance and further is also contained in the resincomposition. Moreover, in the case of a prepreg, the silane couplingagent may be contained in the prepreg as a silane coupling agent coveredon the fibrous base material for surface treatment in advance.

Examples of the silane coupling agent include a silane coupling agenthaving at least one functional group selected from the group consistingof a vinyl group, a styryl group, a methacryloyl group, an acryloylgroup, and a phenylamino group. In other words, examples of this silanecoupling agent include compounds having at least one of a vinyl group, astyryl group, a methacryloyl group, an acryloyl group, or a phenylaminogroup as a reactive functional group, and further a hydrolyzable groupsuch as a methoxy group or an ethoxy group.

Examples of the silane coupling agent include vinyltriethoxysilane andvinyltrimethoxysilane as those having a vinyl group. Examples of thesilane coupling agent include p-styryltrimethoxysilane andp-styryltriethoxysilane as those having a styryl group. Examples of thesilane coupling agent include 3-methacryloxypropyltrimethoxysilane,3-methacryloxypropylmethyldimethoxysilane,3-methacryloxypropyltriethoxysilane,3-methacryloxypropylmethyldiethoxysilane, and3-methacryloxypropylethyldiethoxysilane as those having a methacryloylgroup. Examples of the silane coupling agent include3-acryloxypropyltrimethoxysilane and 3-acryloxypropyltriethoxysilane asthose having an acryloyl group. Examples of the silane coupling agentinclude N-phenyl-3-aminopropyltrimethoxysilane andN-phenyl-3-aminopropyltriethoxysilane as those having a phenylaminogroup.

As described above, the resin composition according to the presentembodiment may contain an initiator (reaction initiator). The curingreaction can proceed even though the resin composition does not containa reaction initiator. However, a reaction initiator may be added sincethere is a case where it is difficult to raise the temperature untilcuring proceeds depending on the process conditions. The reactioninitiator is not particularly limited as long as it can promote thecuring reaction of the polyphenylene ether compound with the curingagent. Specific examples thereof include oxidizing agents such asα,α′-bis(t-butylperoxy-m-isopropyl)benzene,2,5-dimethyl-2,5-di(t-butylperoxy)-3-hexyne, benzoyl peroxide,3,3′,5,5′-tetramethyl-1,4-diphenoquinone, chloranil,2,4,6-tri-t-butylphenoxyl, t-butylperoxyisopropyl monocarbonate, andazobisisobutyronitrile. Moreover, a metal carboxylate can beconcurrently used if necessary. By doing so, the curing reaction can befurther promoted. Among these,α,α′-bis(t-butylperoxy-m-isopropyl)benzene is preferably used.α,α′-bis(t-butylperoxy-m-isopropyl)benzene has a relatively highreaction initiation temperature and thus can suppress the promotion ofthe curing reaction at the time point at which curing is not required,for example, at the time of prepreg drying, and can suppress a decreasein storage stability of the resin composition.α,α′-bis(t-butylperoxy-m-isopropyl)benzene exhibits low volatility, thusdoes not volatilize at the time of prepreg drying and storage, andexhibits favorable stability. In addition, the reaction initiator may beused singly or in combination of two or more kinds thereof.

As described above, the resin composition according to the presentembodiment may contain a filler such as an inorganic filler. Examples ofthe filler include those to be added to enhance the heat resistance andflame retardancy of a cured product of the resin composition, but thefiller is not particularly limited. In addition, the heat resistance,flame retardancy and the like can be further enhanced by containing afiller. Specific examples of the filler include silica such as sphericalsilica, metal oxides such as alumina, titanium oxide, and mica, metalhydroxides such as aluminum hydroxide and magnesium hydroxide, talc,aluminum borate, barium sulfate, and calcium carbonate. As the filler,silica, mica, and talc are preferable and spherical silica is morepreferable among these. The filler may be used singly or in combinationof two or more kinds thereof. The filler may be used as it is, or afiller subjected to a surface treatment with the silane coupling agentmay be used. When a filler is contained, the content thereof (fillercontent) is preferably 20% to 270% by mass, more preferably 30% to 250%by mass with respect to the resin composition. When the content of thefiller (filler content) is as low as this, a resin composition isobtained, which becomes as a cured product having a sufficiently lowcoefficient of thermal expansion when being cured.

(Production Method)

The method for producing the resin composition is not particularlylimited, and examples thereof include a method in which the firststyrene-based block copolymer, the polyphenylene ether compound, and thecuring agent are mixed together so as to have predetermined contents.Specific examples thereof include the method to be described later inthe case of obtaining a varnish-like composition containing an organicsolvent.

By using the resin composition according to the present embodiment, aprepreg, a metal-clad laminate, a wiring board, a metal foil with resin,and a film with resin can be obtained as follows.

[Prepreg]

FIG. 1 is a schematic sectional view illustrating an example of aprepreg 1 according to an embodiment of the present invention.

As illustrated in FIG. 1, the prepreg 1 according to the presentembodiment includes the resin composition or a semi-cured product 2 ofthe resin composition and a fibrous base material 3. This prepreg 1includes the resin composition or the semi-cured product 2 of the resincomposition and the fibrous base material 3 present in the resincomposition or the semi-cured product 2 of the resin composition.

In the present embodiment, the semi-cured product is in a state in whichthe resin composition has been cured to an extent that the resincomposition can be further cured. In other words, the semi-cured productis in a state in which the resin composition has been semi-cured(B-staged). For example, when the resin composition is heated, theviscosity gradually decreases at first, and then curing starts, and thencuring starts, and the viscosity gradually increases. In such a case,the semi-cured state includes a state in which the viscosity has startedto increase but curing is not completed, and the like.

The prepreg to be obtained using the resin composition according to thepresent embodiment may include a semi-cured product of the resincomposition as described above or include the uncured resin compositionitself. In other words, the prepreg may be a prepreg including asemi-cured product of the resin composition (the B-stage resincomposition) and a fibrous base material or a prepreg including theresin composition before being cured (the A-stage resin composition) anda fibrous base material. The resin composition or the semi-cured productof the resin composition may be a dried or heat-dried product of theresin composition.

When manufacturing a prepreg, the resin composition 2 is often preparedin a varnish form and used in order to be impregnated into the fibrousbase material 3 which is a base material for forming the prepreg. Inother words, the resin composition 2 is usually a resin varnish preparedin a varnish form in many cases. Such a varnish-like resin composition(resin varnish) is prepared, for example, as follows.

First, the respective components which can be dissolved in an organicsolvent are introduced into and dissolved in an organic solvent. At thistime, heating may be performed if necessary. Thereafter, componentswhich are used if necessary but are not dissolved in the organic solventare added to and dispersed in the solution until a predetermineddispersion state is achieved using a ball mill, a bead mill, a planetarymixer, a roll mill or the like, whereby a varnish-like resin compositionis prepared. The organic solvent to be used here is not particularlylimited as long as it dissolves the first styrene-based block copolymer,the polyphenylene ether compound, the curing agent, and the like anddoes not inhibit the curing reaction. Specific examples thereof includetoluene and methyl ethyl ketone (MEK).

The method for manufacturing the prepreg is not particularly limited aslong as the prepreg can be manufactured. Specifically, whenmanufacturing a prepreg, the resin composition which has been describedabove and is used in the present embodiment is often prepared in avarnish form and used as a resin varnish as described above.

Specific examples of the fibrous base material include glass cloth,aramid cloth, polyester cloth, a glass nonwoven fabric, an aramidnonwoven fabric, a polyester nonwoven fabric, pulp paper, and linterpaper. When glass cloth is used, a laminate exhibiting excellentmechanical strength is obtained, and glass cloth subjected to flatteningis particularly preferable. Specific examples of the flattening includea method in which glass cloth is continuously pressed at an appropriatepressure using a press roll to flatly compress the yarn. The thicknessof the generally used fibrous base material is, for example, 0.01 mm ormore and 0.3 mm or less.

The method for manufacturing the prepreg is not particularly limited aslong as the prepreg can be manufactured. Specifically, whenmanufacturing a prepreg, the resin composition according to the presentembodiment described above is often prepared in a varnish form and usedas a resin varnish as described above.

Examples of the method for manufacturing the prepreg 1 include a methodin which the fibrous base material 3 is impregnated with the resincomposition 2, for example, the resin composition 2 prepared in avarnish form, and then dried. The fibrous base material 3 is impregnatedwith the resin composition 2 by dipping, coating, and the like. Ifnecessary, the impregnation can be repeated a plurality of times.Moreover, at this time, it is also possible to finally adjust thecomposition and impregnated amount to the desired composition andimpregnated amount by repeating impregnation using a plurality of resincompositions having different compositions and concentrations.

The fibrous base material 3 impregnated with the resin composition(resin varnish) 2 is heated under desired heating conditions, forexample, at 80° C. or more and 180° C. or less for 1 minute or more and10 minutes or less. By heating, the prepreg 1 before being cured(A-stage) or in a semi-cured state (B-stage) is obtained. By theheating, the organic solvent can be decreased or removed by beingvolatilized from the resin varnish.

The resin composition according to the present embodiment is a resincomposition which provides a cured product exhibiting low dielectricproperties and a low coefficient of thermal expansion. For this reason,the prepreg including this resin composition or a semi-cured product ofthis resin composition is a prepreg which provides a cured productexhibiting low dielectric properties and a low coefficient of thermalexpansion. Moreover, a wiring board including an insulating layerexhibiting low dielectric properties and a low coefficient of thermalexpansion can be suitably manufactured using this prepreg.

[Metal-Clad Laminate]

FIG. 2 is a schematic sectional view illustrating an example of ametal-clad laminate 11 according to an embodiment of the presentinvention.

As illustrated in FIG. 2, the metal-clad laminate 11 includes aninsulating layer 12 containing a cured product of the prepreg 1illustrated in FIG. 1 and a metal foil 13 to be laminated together withthe insulating layer 12. In other words, the metal-clad laminate 11includes the insulating layer 12 containing a cured product of a resincomposition and the metal foil 13 provided on the insulating layer 12.In addition, the insulating layer 12 may be formed of a cured product ofthe resin composition or a cured product of the prepreg. In addition,the thickness of the metal foil 13 varies depending on the performanceand the like to be required for the finally obtained wiring board and isnot particularly limited. The thickness of the metal foil 13 can beappropriately set depending on the desired purpose and is preferably,for example, 0.2 to 70 μm. Moreover, examples of the metal foil 13include a copper foil and an aluminum foil, and the metal foil 13 may bea copper foil with carrier which includes a release layer and a carrierfor the improvement in handleability in a case where the metal foil isthin.

The method for manufacturing the metal-clad laminate 11 is notparticularly limited as long as the metal-clad laminate 11 can bemanufactured. Specific examples thereof include a method in which themetal-clad laminate 11 is fabricated using the prepreg 1. Examples ofthis method include a method in which the double-sided metal foil-clador single-sided metal foil-clad laminate 11 is fabricated by stackingone sheet or a plurality of sheets of prepreg 1, further stacking themetal foil 13 such as a copper foil on both or one of upper and lowersurfaces of the prepregs 1, and laminating and integrating the metalfoils 13 and prepregs 1 by heating and pressing. In other words, themetal-clad laminate 11 is obtained by laminating the metal foil 13 onthe prepreg 1 and then performing heating and pressing. Moreover, theheating and pressing conditions can be appropriately set depending onthe thickness of the metal-clad laminate 11 to be manufactured, the kindof the composition of the prepreg 1, and the like. For example, it ispossible to set the temperature to 170° C. to 230° C., the pressure to 2to 5 MPa, and the time to 60 to 150 minutes. Moreover, the metal-cladlaminate may be manufactured without using a prepreg. Examples thereofinclude a method in which a varnish-like resin composition is applied ona metal foil to form a layer containing the resin composition on themetal foil and then heating and pressing is performed.

The resin composition according to the present embodiment is a resincomposition which provides a cured product exhibiting low dielectricproperties and a low coefficient of thermal expansion. For this reason,the metal-clad laminate including an insulating layer containing thecured product of this resin composition is a metal-clad laminateincluding an insulating layer containing a cured product exhibiting lowdielectric properties and a low coefficient of thermal expansion.Moreover, a wiring board including an insulating layer exhibiting lowdielectric properties and a low coefficient of thermal expansion can besuitably manufactured using this metal-clad laminate.

[Wiring Board]

FIG. 3 is a schematic sectional view illustrating an example of a wiringboard 21 according to an embodiment of the present invention.

The wiring board 21 according to the present embodiment is formed of aninsulating layer 12 obtained by curing the prepreg 1 illustrated in FIG.1 and wiring 14 which is laminated together with the insulating layer 12and is formed by partially removing the metal foil 13 as illustrated inFIG. 3. In other words, the wiring board 21 includes the insulatinglayer 12 containing a cured product of a resin composition and thewiring 14 provided on the insulating layer 12. In addition, theinsulating layer 12 may be formed of a cured product of the resincomposition or a cured product of the prepreg.

The method for manufacturing the wiring board 21 is not particularlylimited as long as the wiring board 21 can be manufactured. Specificexamples thereof include a method in which the wiring board 21 isfabricated using the prepreg 1. Examples of this method include a methodin which the wiring board 21, in which wiring is provided as a circuiton the surface of the insulating layer 12, is fabricated by formingwiring through etching and the like of the metal foil 13 on the surfaceof the metal-clad laminate 11 fabricated in the manner described above.In other words, the wiring board 21 is obtained by partially removingthe metal foil 13 on the surface of the metal-clad laminate 11 and thusforming a circuit. In addition, examples of the method for forming acircuit include circuit formation by a semi-additive process (SAP) or amodified semi-additive process (MSAP) in addition to the methoddescribed above. The wiring board 21 includes the insulating layer 12having a high glass transition temperature, excellent flame retardancy,low water absorbing property, and sufficiently suppressed increases indielectric constant and dielectric loss tangent due to water absorptioneven after water absorption.

Such a wiring board is a wiring board including an insulating layercontaining a cured product exhibiting low dielectric properties and alow coefficient of thermal expansion.

[Metal Foil with Resin]

FIG. 4 is a schematic sectional view illustrating an example of a metalfoil with resin 31 according to the present embodiment.

The metal foil with resin 31 according to the present embodimentincludes a resin layer 32 containing the resin composition or asemi-cured product of the resin composition and a metal foil 13 asillustrated in FIG. 4. The metal foil with resin 31 includes the metalfoil 13 on the surface of the resin layer 32. In other words, the metalfoil with resin 31 includes the resin layer 32 and the metal foil 13 tobe laminated together with the resin layer 32. Moreover, the metal foilwith resin 31 may include other layers between the resin layer 32 andthe metal foil 13.

In addition, the resin layer 32 may contain a semi-cured product of theresin composition as described above or may contain the uncured resincomposition. In other words, the metal foil with resin 31 may be a metalfoil with resin including a resin layer containing a semi-cured productof the resin composition (the B-stage resin composition) and a metalfoil or a metal foil with resin including a resin layer containing theresin composition before being cured (the A-stage resin composition) anda metal foil. Moreover, the resin layer only needs to contain the resincomposition or a semi-cured product of the resin composition and may ormay not contain a fibrous base material. The resin composition or thesemi-cured product of the resin composition may be a dried or heat-driedproduct of the resin composition. As the fibrous base material, thosesimilar to the fibrous base materials of the prepreg can be used.

Moreover, as the metal foil, metal foils to be used in metal-cladlaminates can be used without being limited. Examples of the metal foilinclude a copper foil and an aluminum foil.

The metal foil with resin 31 and a film with resin 41 may include acover fill and the like if necessary. By including the cover film, it ispossible to prevent entry of foreign matter and the like. The cover filmis not particularly limited, and examples thereof include a polyolefinfilm, a polyester film, a polymethylpentene film, and films formed byproviding a release agent layer on these films.

The method for manufacturing the metal foil with resin 31 is notparticularly limited as long as the metal foil with resin 31 can bemanufactured. Examples of the method for manufacturing the metal foilwith resin 31 include a method in which the varnish-like resincomposition (resin varnish) is applied on the metal foil 13 and heatedto manufacture the metal foil with resin 31. The varnish-like resincomposition is applied on the metal foil 13 using, for example, a barcoater. The applied resin composition is heated under the conditions of,for example, 40° C. or more and 180° C. or less and 0.1 minute or moreand 10 minutes or less. The heated resin composition is formed as theuncured resin layer 32 on the metal foil 13. By the heating, the organicsolvent can be decreased or removed by being volatilized from the resinvarnish.

The resin composition according to the present embodiment is a resincomposition which provides a cured product exhibiting low dielectricproperties and a low coefficient of thermal expansion. For this reason,the metal foil with resin including a resin layer containing this resincomposition or a semi-cured product of this resin composition is a metalfoil with resin including a resin layer, which provides a cured productexhibiting low dielectric properties and a low coefficient of thermalexpansion. Moreover, this metal foil with resin can be used when awiring board including an insulating layer containing a cured productexhibiting low dielectric properties and a low coefficient of thermalexpansion is suitably manufactured. For example, by laminating the metalfoil with resin on a wiring board, a multilayer wiring board can bemanufactured. As the wiring board obtained by using such a metal foilwith resin, a wiring board including an insulating layer containing acured product exhibiting low dielectric properties and a low coefficientof thermal expansion is obtained.

[Film with Resin]

FIG. 5 is a schematic sectional view illustrating an example of a filmwith resin 41 according to the present embodiment.

The film with resin 41 according to the present embodiment includes aresin layer 42 containing the resin composition or a semi-cured productof the resin composition and a support film 43 as illustrated in FIG. 5.The film with resin 41 includes the resin layer 42 and the support film43 to be laminated together with the resin layer 42. Moreover, the filmwith resin 41 may include other layers between the resin layer 42 andthe support film 43.

In addition, the resin layer 42 may contain a semi-cured product of theresin composition as described above or may contain the uncured resincomposition. In other words, the film with resin 41 may be a film withresin including a resin layer containing a semi-cured product of theresin composition (the B-stage resin composition) and a support film ora film with resin including a resin layer containing the resincomposition before being cured (the A-stage resin composition) and asupport film. Moreover, the resin layer only needs to contain the resincomposition or a semi-cured product of the resin composition and may ormay not contain a fibrous base material. The resin composition or thesemi-cured product of the resin composition may be a dried or heat-driedproduct of the resin composition. As the fibrous base material, thosesimilar to the fibrous base materials of the prepreg can be used.

Moreover, as the support film 43, support film to be used in film withresin can be used without being limited. Examples of the support filminclude electrically insulating films such as a polyester film, apolyethylene terephthalate (PET) film, a polyimide film, a polyparabanicacid film, a polyether ether ketone film, a polyphenylene sulfide film,a polyamide film, a polycarbonate film, and a polyarylate film.

The film with resin 41 may include a cover film and the like ifnecessary. By including a cover film, it is possible to prevent entry offoreign matter and the like. The cover film is not particularly limited,and examples thereof include a polyolefin film, a polyester film, and apolymethylpentene film.

The support film and the cover film may be those subjected to surfacetreatments such as a matt treatment, a corona treatment, a releasetreatment, and a roughening treatment if necessary.

The method for manufacturing the film with resin 41 is not particularlylimited as long as the film with resin 41 can be manufactured. Examplesof the method for manufacturing the film with resin 41 include a methodin which the varnish-like resin composition (resin varnish) is appliedon the support film 43 and heated to manufacture the film with resin 41.The varnish-like resin composition is applied on the support film 43using, for example, a bar coater. The applied resin composition isheated under the conditions of, for example, 40° C. or more and 180° C.or less and 0.1 minute or more and 10 minutes or less. The heated resincomposition is formed as the uncured resin layer 42 on the support film43. By the heating, the organic solvent can be decreased or removed bybeing volatilized from the resin varnish.

The resin composition according to the present embodiment is a resincomposition which provides a cured product exhibiting low dielectricproperties and a low coefficient of thermal expansion. For this reason,the film with resin including a resin layer containing this resincomposition or a semi-cured product of this resin composition is a filmwith resin including a resin layer, which provides a cured productexhibiting low dielectric properties and a low coefficient of thermalexpansion. Moreover, this film with resin can be used when a wiringboard including an insulating layer exhibiting low dielectric propertiesand a low coefficient of thermal expansion is suitably manufactured. Amultilayer wiring board can be manufactured, for example, by laminatingthe film with resin on a wiring board and then peeling off the supportfilm from the film with resin or by peeling off the support film fromthe film with resin and then laminating the film with resin on a wiringboard. As the wiring board obtained by using such a film with resin, awiring board including an insulating layer exhibiting low dielectricproperties and a low coefficient of thermal expansion is obtained.

The present specification discloses various aspects of a technique asdescribed above, but the main technique is summarized below.

The resin composition according to an aspect of the present invention isa resin composition containing a first styrene-based block copolymerhaving a hardness of 70 or less, a polyphenylene ether compound havingat least one of a group represented by the following Formula (1) and agroup represented by the following Formula (2) in the molecule, and acuring agent.

In Formula (1), p represents 0 to 10, Z represents an arylene group, andR₁ to R₃ each independently represent a hydrogen atom or an alkyl group.

In Formula (2), R₄ represents a hydrogen atom or an alkyl group.

According to such a configuration, it is possible to provide a resincomposition, which provides a cured product exhibiting low dielectricproperties and a low coefficient of thermal expansion.

This is considered to be due to the following.

First, it is considered that a cured product which maintains theexcellent low dielectric properties of polyphenylene ether is obtainedfrom the resin composition by curing the polyphenylene ether compoundtogether with the curing agent even though the first styrene-based blockcopolymer is contained. It is considered that a cured product having alow coefficient of thermal expansion is obtained since the resincomposition contains the first styrene-based block copolymer having ahardness of 70 or less. From these facts, it is considered that theresin composition provides a cured product exhibiting low dielectricproperties and a low coefficient of thermal expansion.

In the resin composition, it is preferable that the content of astructural unit derived from at least one of styrene and a styrenederivative is 1% to 20% by mass in the first styrene-based blockcopolymer.

According to such a configuration, a resin composition is obtained,which becomes a cured product having a lower coefficient of thermalexpansion while maintaining excellent low dielectric properties whenbeing cured.

In the resin composition, it is preferable that the weight averagemolecular weight of the first styrene-based block copolymer is 10,000 to200,000.

According to such a configuration, a resin composition is obtained,which becomes a cured product having a lower coefficient of thermalexpansion while maintaining excellent low dielectric properties whenbeing cured.

In the resin composition, it is preferable that the first styrene-basedblock copolymer includes at least one selected from the group consistingof a methylstyrene (ethylene/butylene) methylstyrene copolymer, amethylstyrene (ethylene-ethylene/propylene) methylstyrene copolymer, astyrene isoprene copolymer, a styrene isoprene styrene copolymer, astyrene (ethylene/butylene) styrene copolymer, a styrene(ethylene-ethylene/propylene) styrene copolymer, a styrene butadienestyrene copolymer, a styrene (butadiene/butylene) styrene copolymer, astyrene isobutylene styrene copolymer, and any hydrogenated product ofthese copolymers.

According to such a configuration, a resin composition is obtained,which becomes a cured product having a lower coefficient of thermalexpansion while maintaining excellent low dielectric properties whenbeing cured.

In the resin composition, it is preferable that the curing agentcontains an allyl compound.

According to such a configuration, it is possible to provide a resincomposition, which provides a cured product exhibiting low dielectricproperties and a low coefficient of thermal expansion and a high glasstransition temperature. It is considered that this is because the allylcompound can suitably cure the polyphenylene ether compound togetherwith the first styrene-based block copolymer.

In the resin composition, it is preferable that the allyl compoundincludes an allyl isocyanurate compound having two or more allyl groupsin the molecule.

According to such a configuration, it is possible to provide a resincomposition, which provides a cured product exhibiting low dielectricproperties and a low coefficient of thermal expansion and a high glasstransition temperature. It is considered that this is because the allylisocyanurate compound can suitably cure the polyphenylene ether compoundtogether with the first styrene-based block copolymer.

In the resin composition, it is preferable that the content of the firststyrene-based block copolymer is 20 to 60 parts by mass with respect to100 parts by mass of the sum of the first styrene-based block copolymer,the polyphenylene ether compound, and the curing agent.

According to such a configuration, a resin composition is obtained,which becomes a cured product having a lower coefficient of thermalexpansion while maintaining excellent low dielectric properties whenbeing cured.

In the resin composition, it is preferable that a second styrene-basedblock copolymer having a hardness of more than 70 is further contained.

According to such a configuration, there is provided a resincomposition, which suitably provides a cured product exhibiting lowdielectric properties and a low coefficient of thermal expansion. Whenthe styrene-based block copolymer contained in the resin composition issoft (has a low hardness), the contained components tend to be easilyseparated from each other when the obtained resin composition is formedinto a varnish. When the content of the first styrene-based blockcopolymer is high, the contained components tend to be easily separatedfrom each other when the obtained resin composition is formed into avarnish. By containing not only the first styrene-based block copolymerbut also the second styrene-based block copolymer having a hardness ofmore than 70, a resin composition is obtained, in which the separationof the contained components is suppressed while the low coefficient ofthermal expansion is maintained. Hence, the resin composition suitablyprovides a cured product exhibiting low dielectric properties and a lowcoefficient of thermal expansion.

In the resin composition, it is preferable that the total content of thefirst styrene-based block copolymer and the second styrene-based blockcopolymer is 20 to 60 parts by mass with respect to 100 parts by mass ofthe sum of the first styrene-based block copolymer, the polyphenyleneether compound, the curing agent, and the second styrene-based blockcopolymer.

According to such a configuration, there is provided a resincomposition, which more suitably provides a cured product exhibiting lowdielectric properties and a low coefficient of thermal expansion.

In the resin composition, it is preferable that the content of thesecond styrene-based block copolymer is 1 to 50 parts by mass withrespect to 100 parts by mass of the sum of the first styrene-based blockcopolymer and the second styrene-based block copolymer.

According to such a configuration, there is provided a resincomposition, which more suitably provides a cured product exhibiting lowdielectric properties and a low coefficient of thermal expansion.

In the resin composition, it is preferable that the second styrene-basedblock copolymer includes at least one selected from the group consistingof a methylstyrene (ethylene/butylene) methylstyrene copolymer, amethylstyrene (ethylene-ethylene/propylene) methylstyrene copolymer, astyrene isoprene copolymer, a styrene isoprene styrene copolymer, astyrene (ethylene/butylene) styrene copolymer, a styrene(ethylene-ethylene/propylene) styrene copolymer, a styrene butadienestyrene copolymer, a styrene (butadiene/butylene) styrene copolymer, astyrene isobutylene styrene copolymer, and any hydrogenated product ofthese copolymers.

According to such a configuration, there is provided a resincomposition, which more suitably provides a cured product exhibiting lowdielectric properties and a low coefficient of thermal expansion.

In the resin composition, it is preferable that the polyphenylene ethercompound includes a polyphenylene ether compound having the grouprepresented by Formula (2) in the molecule.

According to such a configuration, it is possible to provide a resincomposition, which provides a cured product exhibiting low dielectricproperties and a low coefficient of thermal expansion and a high glasstransition temperature.

The prepreg according to another aspect of the present invention is aprepreg including the resin composition or a semi-cured product of theresin composition, and a fibrous base material.

According to such a configuration, it is possible to provide a prepreg,which provides a cured product exhibiting low dielectric properties anda low coefficient of thermal expansion.

The film with resin according to another aspect of the present inventionis a film with resin including a resin layer containing the resincomposition or a semi-cured product of the resin composition, and asupport film.

According to such a configuration, it is possible to provide a film withresin including a resin layer, which provides a cured product exhibitinglow dielectric properties and a low coefficient of thermal expansion.

The metal foil with resin according to another aspect of the presentinvention is a metal foil with resin including a resin layer containingthe resin composition or a semi-cured product of the resin composition,and a metal foil.

According to such a configuration, it is possible to provide a metalfoil with resin including a resin layer, which provides a cured productexhibiting low dielectric properties and a low coefficient of thermalexpansion.

The metal-clad laminate according to another aspect of the presentinvention is a metal-clad laminate including an insulating layercontaining a cured product of the resin composition or a cured productof the prepreg, and a metal foil.

According to such a configuration, it is possible to provide ametal-clad laminate including an insulating layer containing a curedproduct exhibiting low dielectric properties and a low coefficient ofthermal expansion.

The wiring board according to another aspect of the present invention isa wiring board including an insulating layer containing a cured productof the resin composition or a cured product of the prepreg, and wiring.

According to such a configuration, it is possible to provide a wiringboard including an insulating layer containing a cured productexhibiting low dielectric properties and a low coefficient of thermalexpansion.

According to the present invention, it is possible to provide a resincomposition, which provides a cured product exhibiting low dielectricproperties and a low coefficient of thermal expansion. In addition,according to the present invention, a prepreg, a film with resin, ametal foil with resin, a metal-clad laminate, and a wiring board whichare obtained using the resin composition are provided.

Hereinafter, the present invention will be described more specificallywith reference to examples, but the scope of the present invention isnot limited thereto.

EXAMPLES Examples 1 to 9 and Comparative Examples 1 to 3

The respective components to be used when a resin composition isprepared in the present Examples will be described.

(Styrene-Based Block Copolymer: Hardness of 70 or Less)

Septon 2063: Styrene isoprene styrene copolymer (Septon 2063manufactured by Kuraray Co., Ltd., tensile modulus at 25° C.: 0.4 MPa,durometer hardness: 36, content of structural unit derived from styrene:13% by mass, weight average molecular weight: 95000)

Tuftec H1221: Styrene (ethylene/butylene) styrene copolymer (TuftecH1221 manufactured by Asahi Kasei Corporation, tensile modulus at 25°C.: 1.5 MPa, durometer hardness: 42, content of structural unit derivedfrom styrene: 12% by mass, weight average molecular weight: 150000)

Tuftec H1052: Hydrogenated styrene (ethylene/butylene) styrene copolymer(Tuftec H1052 manufactured by Asahi Kasei Corporation, tensile modulusat 25° C.: 5 MPa, durometer hardness: 67, content of structural unitderived from styrene: 20% by mass, weight average molecular weight:91000)

(Styrene-Based Block Copolymer: Hardness of More than 70)

Septon V9827: Hydrogenated methylstyrene (ethylene/butylene)methylstyrene copolymer (Septon V9827 manufactured by Kuraray Co., Ltd.,tensile modulus at 25° C.: more than 10 MPa, durometer hardness: 78,content of structural unit derived from styrene: 30% by mass, weightaverage molecular weight: 92000)

Tuftec H1053: Hydrogenated styrene (ethylene/butylene) styrene copolymer(Tuftec H1053 manufactured by Asahi Kasei Corporation, tensile modulusat 25° C.: 62 MPa, durometer hardness: 79, content of structural unitderived from styrene: 29% by mass, weight average molecular weight:71000)

Tuftec H1517: Hydrogenated styrene (ethylene/butylene) styrene copolymer(Tuftec H1517 manufactured by Asahi Kasei Corporation, tensile modulusat 25° C.: 288 MPa, durometer hardness: 92, content of structural unitderived from styrene: 43% by mass, weight average molecular weight:90000)

(Polyphenylene Ether Compound)

Modified PPE1: Polyphenylene ether compound having a methacryloyl groupat the terminal (modified polyphenylene ether obtained by modifying theterminal hydroxyl groups of polyphenylene ether with a methacryloylgroup, a modified polyphenylene ether compound represented by Formula(12), where Y is a dimethylmethylene group (a group represented byFormula (9), where R₃₃ and R₃₄ are a methyl group), SA9000 manufacturedby SABIC Innovative Plastics, weight average molecular weight Mw: 2000,number of terminal functional groups: 2)

Modified PPE2: Polyphenylene ether compound having a vinylbenzyl group(ethenylbenzyl group) at the terminal (a modified polyphenylene ethercompound obtained by reacting polyphenylene ether withchloromethylstyrene).

More specifically, a modified polyphenylene ether compound obtained byperforming a reaction as follows.

First, 200 g of polyphenylene ether (SA90 manufactured by SABICInnovative Plastics, number of terminal hydroxyl groups: 2, weightaverage molecular weight Mw: 1700), 30 g of a mixture containingp-chloromethylstyrene and m-chloromethylstyrene at a mass ratio of 50:50(chloromethylstyrene: CMS manufactured by Tokyo Chemical Industry Co.,Ltd.), 1.227 g of tetra-n-butylammonium bromide as a phase transfercatalyst, and 400 g of toluene were introduced into a 1-literthree-necked flask equipped with a temperature controller, a stirrer,cooling equipment, and a dropping funnel and stirred. The mixture wasstirred until polyphenylene ether, chloromethylstyrene, andtetra-n-butylammonium bromide were dissolved in toluene. At that time,the mixture was gradually heated until the liquid temperature finallyreached 75° C. Thereafter, an aqueous sodium hydroxide solution (20 g ofsodium hydroxide/20 g of water) as an alkali metal hydroxide was addeddropwise to the solution over 20 minutes. Thereafter, the mixture wasfurther stirred at 75° C. for 4 hours. Next, the resultant in the flaskwas neutralized with hydrochloric acid at 10% by mass and then a largeamount of methanol was added into the flask. By doing so, a precipitatewas generated in the liquid in the flask. In other words, the productcontained in the reaction solution in the flask was reprecipitated.Thereafter, this precipitate was taken out by filtration, washed threetimes with a mixed solution of methanol and water contained at a massratio of 80:20, and then dried under reduced pressure at 80° C. for 3hours.

The obtained solid was analyzed by ¹H-NMR (400 MHz, CDCl₃, TMS). As aresult of NMR measurement, a peak attributed to a vinylbenzyl group(ethenylbenzyl group) was observed at 5 to 7 ppm. This made it possibleto confirm that the obtained solid was a modified polyphenylene ethercompound having a vinylbenzyl group (ethenylbenzyl group) as thesubstituent at the molecular terminal in the molecule. Specifically, itwas confirmed that the solid obtained was ethenylbenzylatedpolyphenylene ether. This obtained modified polyphenylene ether compoundwas a modified polyphenylene ether compound represented by Formula (11),where Y was a dimethylmethylene group (a group represented by Formula(9), where R₃₃ and R₃₄ were a methyl group), Z was a phenylene group, R₁to R₃ were a hydrogen atom, and p was 1.

The number of terminal functional groups in the modified polyphenyleneether was measured as follows.

First, the modified polyphenylene ether was accurately weighed. Theweight at that time is defined as X (mg). Thereafter, this modifiedpolyphenylene ether weighed was dissolved in 25 mL of methylenechloride, 100 μL of an ethanol solution of tetraethylammonium hydroxide(TEAH) at 10% by mass (TEAH:ethanol (volume ratio)=15:85) was added tothe solution, and then the absorbance (Abs) of this mixture at 318 nmwas measured using a UV spectrophotometer (UV-1600 manufactured byShimadzu Corporation). Thereafter, the number of terminal hydroxylgroups in the modified polyphenylene ether was calculated from themeasurement result using the following equation.

Residual OH amount (μmol/g)=[(25×Abs)/(ε×OPL×X)]×10⁶

Here, ε indicates the extinction coefficient and is 4700 L/mol·cm. Inaddition, OPL indicates the cell path length and is 1 cm.

Moreover, since the calculated residual OH amount (the number ofterminal hydroxyl groups) in the modified polyphenylene ether is almostzero, it was found that the hydroxyl groups in the polyphenylene etherbefore being modified are almost modified. From this fact, it was foundthat the number of terminal hydroxyl groups decreased from the number ofterminal hydroxyl groups in polyphenylene ether before being modified isthe number of terminal hydroxyl groups in polyphenylene ether beforebeing modified. In other words, it was found that the number of terminalhydroxyl groups in polyphenylene ether before being modified is thenumber of terminal functional groups in the modified polyphenyleneether. In other words, the number of terminal functional groups was two.

The intrinsic viscosity (IV) of the modified polyphenylene ether wasmeasured in methylene chloride at 25° C. Specifically, the intrinsicviscosity (IV) of the modified polyphenylene ether was measured in amethylene chloride solution (liquid temperature: 25° C.) of the modifiedpolyphenylene ether at 0.18 g/45 ml using a viscometer (AVS500 ViscoSystem manufactured by SCHOTT Instruments GmbH). As a result, theintrinsic viscosity (IV) of the modified polyphenylene ether was 0.086dl/g.

The molecular weight distribution of the modified polyphenylene etherwas measured by GPC. The weight average molecular weight (Mw) wascalculated from the obtained molecular weight distribution. As a result,Mw was 1,900.

(Curing Agent: Allyl Compound)

TAIL: Triallyl isocyanurate (TAIC manufactured by Nihon Kasei CO., LTD.)

TMPT: Trimethylolpropane trimethacrylate (TMPT manufactured bySHIN-NAKAMURA CHEMICAL CO., LTD.)

(Others)

Initiator: α,α′-Di(t-butylperoxy)diisopropylbenzene (Perbutyl P (PBP)manufactured by NOF CORPORATION)

Filler: Silica treated with vinylsilane (SV-C2 manufactured by AdmatechsCompany Limited, average particle size: 1.5 μm)

[Preparation Method]

First, the respective components other than the filler were added to andmixed in toluene at the compositions (parts by mass) presented in Table1 so that the solid concentration was 50% by mass. The mixture wasstirred for 60 minutes. Thereafter, the filler was added to anddispersed in the obtained liquid using a bead mill. By doing so, avarnish-like resin composition (varnish) was obtained.

Next, an evaluation substrate (cured product of metal foil with resin)was obtained as follows.

The obtained varnish was applied to a metal foil (copper foil, 3EC-VLPmanufactured by MITSUI MINING & SMELTING CO., LTD., thickness: 12 μm) soas to have a thickness of 50 μm, and heated at 120° C. for 3 minutes toobtain a metal foil with resin. Two sheets of the obtained metal foilwith resin were then stacked so that the resin layers were in contactwith each other. The resin layer of the metal foil with resin was curedby heating and pressurizing this as a body to be pressurized for 2 hoursunder the conditions of 200° C. and a pressure of 4 MPa in a vacuum.This was used as an evaluation substrate (cured product of metal foilwith resin). The thickness of the resin layer (thickness other than themetal foil) in the evaluation substrate was 100 μm.

The evaluation substrate (cured product of metal foil with resin)prepared as described above was evaluated by the methods describedbelow.

[Dielectric Properties (Relative Dielectric Constant)]

The relative dielectric constant of the laminate obtained by removingthe copper foil from the evaluation substrate (cured product of metalfoil with resin) at 10 GHz was measured by a cavity perturbation method.Specifically, the relative dielectric constant of the laminate obtainedby removing the copper foil from the evaluation substrate at 10 GHz wasmeasured using a network analyzer (N5230A manufactured by AgilentTechnologies, Inc.).

[Coefficient of Linear Expansion (CTE)]

The coefficient of linear expansion in the plane direction of thelaminate obtained by removing the copper foil from the evaluationsubstrate (cured product of metal foil with resin) was measured in thetensile mode by a method conforming to JIS C6481. The measurement wasperformed under the measurement conditions of a rate of temperature riseof 10° C./min and a temperature range of less than Tg, specifically, at50° C. to 100° C. using a thermomechanical analyzer (TMA) (TMA/SS7000manufactured by Hitachi High-Tech Science Corporation).

[Glass Transition Temperature (Tg)]

The Tg of the laminate obtained by removing the copper foil from theevaluation substrate (cured product of metal foil with resin) wasmeasured using a viscoelastic spectrometer “DMS6100” manufactured bySeiko Instruments Inc. At this time, the dynamic mechanical analysis(DMA) was performed at a frequency of 10 Hz using a tension module, andthe temperature at which tan δ was the maximum when the temperature wasraised from room temperature to 320° C. under the condition of a rate oftemperature rise of 5° C./min was defined as Tg (° C.).

[State of Varnish]

A varnish (not containing filler) containing the resin compositionaccording to each of Examples and Comparative Examples was prepared bythe same method as the method for preparing a varnish except that thefiller was not contained. Each varnish (not containing filler) was leftat room temperature for 1 day after preparation, and then the state ofthe varnish was visually examined. The state of the varnish wasevaluated as “stable” when the varnish was confirmed to be one layer(single layer), and the state of the varnish was evaluated as“separated” when the varnish was confirmed to be two layers (separatedinto two layers).

The results of the respective evaluations are presented in Table 1.

TABLE 1 Examples 1 2 3 4 5 6 Composition Styrene-based Hardness ofSepton2063 30 — — — — — (parts by block 70 or less Tuftec H1221 — 20 2015 20 14 mass) copolymer Tuftec H1052 — — — 15 — — Hardness of SeptonV9827 — 10 — — 10 — more than 70 Tuftec H1053 — — — — — — Tuftec H1517 —— 10 — — — Modified PPE1 35 35 35 35 35 43 Modified PPE2 — — — — — —Curing agent TAIC 35 35 35 35 — 43 TMPT — — — 35 — Initiator Perbutyl P1 1 1 1 1 1 Filler 150 150 150 150 150 150 Evaluation Relativedielectric constant 2.65 2.65 2.65 2.65 2.60 2.80 Coefficient of linearexpansion 30 32 35 31 33 35 Glass transition temperature Tg (° C.) 255260 255 255 230 260 State of varnish Separated Stable Stable SeparatedStable Separated Examples Comparative Example 7 8 9 1 2 3 CompositionStyrene-based Hardness of Septon2063 — — — — — — (parts by block 70 orless Tuftec H1221 62 35 20 — — — mass) copolymer Tuftec H1052 — — — — —— Hardness of Septon V9827 — — — 30 — — more than 70 Tuftec H1053 — — —— 30 — Tuftec H1517 — 15 10 — — — Modified PPE1 19 25 — 35 35 50Modified PPE2 — — 35 — — — Curing agent TAIC 19 25 35 35 35 50 TMPT — —— — — — Initiator Perbutyl P 1 1 1 1 1 1 Filler 150 150 150 150 150 150Evaluation Relative dielectric constant 2.50 2.55 2.65 2.70 2.70 2.90Coefficient of linear expansion 35 36 34 37 50 35 Glass transitiontemperature Tg (° C.) 245 250 235 260 255 260 State of varnish SeparatedStable Stable Stable Stable Stable

As can be seen from Table 1, in a resin composition containing thepolyphenylene ether compound and the cured product, in a case where thefirst styrene-based block copolymer having a hardness of 70 or less wascontained (Examples 1 to 9), the dielectric properties were low suchthat the relative dielectric constant was 2.8 or less, and thecoefficient of linear expansion was as low as less than 37. It was foundthat the coefficient of linear expansion in Examples 1 to 9 was lowercompared with those in a case where a second styrene-based blockcopolymer having a hardness of more than 70 was contained instead of thefirst styrene-based block copolymer (Comparative Example 1 andComparative Example 2). The relative dielectric constant in Examples 1to 9 was lower compared with those in a case where the firststyrene-based block copolymer was not contained and the secondstyrene-based block copolymer was not contained (Comparative Example 3).Consequently, it has been found that both low dielectric properties anda low coefficient of thermal expansion can be achieved at the same timeby containing the first styrene-based block copolymer having a hardnessof 70 or less in a resin composition containing the polyphenylene ethercompound and the cured product.

It was found that the stability of the varnish was also higher in thecase of containing not only the first styrene-based block copolymer butalso the second styrene-based block copolymer (Example 2, Example 3,Example 5, Example 8, and Example 9) compared with that in the case ofcontaining the first styrene-based block copolymer without containingthe second styrene-based block copolymer (Example 1, Example 4, Example6, and Example 7). From this fact, it has been found that the containedcomponents are hardly separated from each other when the resincomposition is formed into a varnish by using the first styrene-basedblock copolymer and the second styrene-based block copolymerconcurrently.

In a case where the total content of the first styrene-based blockcopolymer and the second styrene-based block copolymer is 30 parts bymass with respect to 100 parts by mass of the total mass of the firststyrene-based block copolymer, the polyphenylene ether compound, thecuring agent, and the second styrene block copolymer (Examples 1 to 4),the relative dielectric constant was lower than in a case where thetotal content was 14 parts by mass (Example 6), and the glass transitiontemperature was higher than in a case where the total content was 62parts by mass (Example 7). Also from this fact, it can be seen that thetotal content of the first styrene-based block copolymer and the secondstyrene-based block copolymer is preferably 20 to 60 parts by mass withrespect to 100 parts by mass of the total mass.

In a case where modified PPE1, which is a polyphenylene ether compoundhaving a methacryloyl group at the terminal, was used (Example 3), theglass transition temperature was higher compared with that in Example 9,which was similar to Example 3 except that modified PPE2, which is apolyphenylene ether compound having a vinylbenzyl group (ethenylbenzylgroup) at the terminal, was used. From this fact, it can be seen that apolyphenylene ether compound having the group represented by Formula (2)in the molecule is preferable.

In a case where TAIC was used as a curing agent (Example 2), the glasstransition temperature was higher compared with that in Example 5, whichwas similar to Example 2 except that TMPT was used. Also from this fact,it can be seen that the curing agent preferably contains an allylcompound such as an allyl isocyanurate compound having two or more allylgroups in the molecule.

This application is based on Japanese Patent Application No. 2019-132005filed on Jul. 17, 2019, the contents of which are included in thepresent application.

In order to express the present invention, the present invention hasbeen described above appropriately and sufficiently through theembodiments. However, it should be recognized by those skilled in theart that changes and/or improvements of the above-described embodimentscan be readily made. Accordingly, changes or improvements made by thoseskilled in the art shall be construed as being included in the scope ofthe claims unless otherwise the changes or improvements are at the levelwhich departs from the scope of the appended claims.

INDUSTRIAL APPLICABILITY

According to the present invention, there is provided a resincomposition, which provides a cured product exhibiting low dielectricproperties and a low coefficient of thermal expansion. In addition,according to the present invention, a prepreg, a film with resin, ametal foil with resin, a metal-clad laminate, and a wiring board whichare obtained using the resin composition are provided.

1. A resin composition comprising: a first styrene-based block copolymerhaving a hardness of 20 to 70; a polyphenylene ether compound having atleast one of a group represented by the following Formula (1) and agroup represented by the following Formula (2) in a molecule; and acuring agent:

(in Formula (1), p represents 0 to 10, Z represents an arylene group,and R₁ to R₃ each independently represent a hydrogen atom or an alkylgroup),

(in Formula (2), R₄ represents a hydrogen atom or an alkyl group). 2.The resin composition according to claim 1, wherein a content of astructural unit derived from at least one of styrene and a styrenederivative is 1% to 20% by mass in the first styrene-based blockcopolymer.
 3. The resin composition according to claim 1, wherein thefirst styrene-based block copolymer has a weight average molecularweight of 10,000 to 200,000.
 4. The resin composition according to claim1, wherein the first styrene-based block copolymer includes at least oneselected from the group consisting of a methylstyrene(ethylene/butylene) methylstyrene copolymer, a methylstyrene(ethylene-ethylene/propylene) methylstyrene copolymer, a styreneisoprene copolymer, a styrene isoprene styrene copolymer, a styrene(ethylene/butylene) styrene copolymer, a styrene(ethylene-ethylene/propylene) styrene copolymer, a styrene butadienestyrene copolymer, a styrene (butadiene/butylene) styrene copolymer, astyrene isobutylene styrene copolymer, and any hydrogenated product ofthese copolymers.
 5. The resin composition according to claim 1, whereinthe curing agent contains an allyl compound.
 6. The resin compositionaccording to claim 5, wherein the allyl compound includes an allylisocyanurate compound having two or more allyl groups in a molecule. 7.The resin composition according to claim 1, wherein a content of thefirst styrene-based block copolymer is 20 to 60 parts by mass withrespect to 100 parts by mass of a sum of the first styrene-based blockcopolymer, the polyphenylene ether compound, and the curing agent. 8.The resin composition according to claim 1, further comprising a secondstyrene-based block copolymer having a hardness of more than
 70. 9. Theresin composition according to claim 8, wherein a total content of thefirst styrene-based block copolymer and the second styrene-based blockcopolymer is 20 to 60 parts by mass with respect to 100 parts by mass ofa sum of the first styrene-based block copolymer, the polyphenyleneether compound, the curing agent, and the second styrene-based blockcopolymer.
 10. The resin composition according to claim 8, wherein acontent of the second styrene-based block copolymer is 1 to 50 parts bymass with respect to 100 parts by mass of a sum of the firststyrene-based block copolymer and the second styrene-based blockcopolymer.
 11. The resin composition according to claim 8, wherein thesecond styrene-based block copolymer includes at least one selected fromthe group consisting of a methylstyrene (ethylene/butylene)methylstyrene copolymer, a methylstyrene (ethylene-ethylene/propylene)methylstyrene copolymer, a styrene isoprene copolymer, a styreneisoprene styrene copolymer, a styrene (ethylene/butylene) styrenecopolymer, a styrene (ethylene-ethylene/propylene) styrene copolymer, astyrene butadiene styrene copolymer, a styrene (butadiene/butylene)styrene copolymer, a styrene isobutylene styrene copolymer, and anyhydrogenated product of these copolymers.
 12. The resin compositionaccording to claim 1, wherein the polyphenylene ether compound includesa polyphenylene ether compound having the group represented by Formula(2) in a molecule.
 13. A prepreg comprising: the resin compositionaccording to claim 1 or a semi-cured product of the resin composition;and a fibrous base material.
 14. A film with resin comprising: a resinlayer containing the resin composition according to claim 1 or asemi-cured product of the resin composition; and a support film.
 15. Ametal foil with resin comprising: a resin layer containing the resincomposition according to claim 1 or a semi-cured product of the resincomposition; and a metal foil.
 16. A metal-clad laminate comprising: aninsulating layer containing a cured product of the resin compositionaccording to claim 1; and a metal foil.
 17. A wiring board comprising:an insulating layer containing a cured product of the resin compositionaccording to claim 1; and wiring.
 18. A metal-clad laminate comprising:an insulating layer containing a cured product of the prepreg accordingto claim 13; and a metal foil.
 19. A wiring board comprising: aninsulating layer containing a cured product of the prepreg according toclaim 13; and wiring.